This application is a continuation of International PCT Application No. PCT/JP99/00479 filed on Feb. 4, 1999.
1. Field of the Invention
The present invention relates to a projective exposure apparatus for exposing a desired pattern onto a liquid crystal or semiconductor substrate, etc.
2. Description of the Related Art
FIG. 1 shows the configuration of a conventional projective exposure apparatus 1 used in producing a liquid crystal display (LCD). The projective exposure apparatus 1 is a projective exposure apparatus in a step-and-repeat system. With the configuration, an LCD pattern formed on a reticle or a mask (hereinafter referred to as a reticle) 3 is irradiated by an illuminating optical system 2, and is exposed onto a predetermined exposure area of a plate 6 which is a rectangular glass substrate placed on an XY stage 5 by a projective optical system 4. When a pattern is transferred by the exposure, the plate 6 is moved by a predetermined distance by moving the XY stage 5, and the LCD pattern is exposed onto another exposure area. Thus, the process of exposing the LCD pattern is repeated for predetermined times. Then, the reticle 3 is replaced with another reticle by a reticle exchange mechanism 10, the LCD pattern on the replacing reticle is sequentially exposed on a predetermined exposure area for predetermined times, and a plurality of reticle patterns are transferred to the entire plate 6.
In the above described exposure apparatus in the step-and-repeat system, the position of the plate 6 on the XY stage 5 is correctly monitored by a laser interferometer 7, and the coordinates of the position are designated. The alignment of the reticle 3 is performed by a reticle alignment system 8, and the alignment of the plate 6 is performed by a plate alignment system 9.
FIG. 2 shows an example of an LCD pattern transferred to the plate 6 by the projective exposure apparatus 1. As shown in FIG. 2, in transferring an LCD pattern, the pattern is divided into, for example, six patterns of A, B, C, D, E, and F. At each joint portion between patterns, a small amount of overlap exposure is carried out, and the patterns are exposed onto 6 positions (6 sections for 6 patterns). These 6 patterns are formed on 6 respective reticles. The six patterns are generated by repeating the exposure with the reticles replaced, thereby forming the entire LCD pattern as shown in the attached drawings.
In exposing a pattern in the above described screen generating method, there can be a discrepancy occurring at a joint portion between patterns as shown in FIGS. 3A, 3B, and 3C due to an alignment error of the reticle 3 and the plate 6, the distortion of the projective optical system 4, etc. That is, if a pattern to be transferred indicates a rotation error, or if there is an error due to the discrepancy of patterns at the positions of the patterns A and B to be transferred when a pattern is generated, then there can be the discrepancy at the joint of the exposed patterns as shown in FIGS. 3A and 3B. In addition, as shown in FIG. 3C, when patterns Axe2x80x2 and Bxe2x80x2 (in solid lines) respectively overlap as the second layer the patterns A and B (in dotted lines) formed by the exposure of the first layer, there can be a discrepancy at the overlap between the first and the second layers. Furthermore, there can be a discrepancy at a joint portion or an overlap error occurring by the distortion of a projection lens. There also can be a discrepancy by a patterning error occurring when a patterning process is performed by exposing a pattern onto a reticle.
When an error occurs by the above described various factors, there arises the problem that an LCD substrate generated by the exposing process cannot have expected characteristics. To solve the problem, there has been a method developed to optimize the amount of amendment (amendment value) to cancel various errors when a pattern is exposed. In this method, the amount of discrepancy between patterns is measured from the transferred image obtained by trial exposure of a pattern, an amendment value is computed from the measured amount, and an amendment is made using the amendment value such that the discrepancy can be removed when the pattern is actually exposed.
To make the above described amendment, it is necessary to set the evaluation position (evaluation point) to evaluate the amount of discrepancy at the joint and the overlap of patterns, and to know the coordinates of the evaluation position on the reticle or the pattern projection area (plate). Furthermore, in a case where the erorr in the joint potion in to be amended, as shown in FIG. 3B, it is necessary to amend the position of the reticle of the pattern B upward when the pattern A is a reference pattern while it is necessary to amend the position of the reticle of the pattern A downward when the pattern B is a reference pattern. Thus, the error amending process has been very complicated. However, the conventional apparatus does not have the function of computing the coordinates of an evaluation position, but an operator manually reads the coordinates of a number of evaluation positions on a plate. The manual settings of coordinates are a laborious operation requiring a very long time. Especially when a plate is large, the evaluation point should reach approximately 100, and the operation is a large load in generating a substrate.
The above described problem can be caused in a projective exposure apparatus in the step-and-repeat system for a semiconductor element, image pickup device (CCD, etc.), and thin film magnetic head, etc. as well as a projective exposure apparatus in the step-and-repeat system for an LCD.
In addition, such a problem can also be caused in another type of projective exposure apparatus. Actually, a projective exposure apparatus can be a projective exposure apparatus in a scanning system, an electron beam (EB) projective exposure apparatus, etc. in addition to the projective exposure apparatuses in the step-and-repeat system.
The present invention has been developed to solve the above described problems, and aims at correctly designating an evaluation point and setting the coordinates on the reticle or the plate within a short time, and improving the efficiency of the pattern exposing operation.
To solve the above described problems, an embodiment of the present invention is described below by referring to FIGS. 4 through 6, 11 and 13. According to various embodiments, the exposure apparatus exposes a pattern on a reticle (3) onto the exposure area of a substrate (6), and includes a display unit (22) for displaying a shot map showing the exposure area, a designation unit (23) for designating an evaluation position on the shot map, and an output unit (21, 22) for outputting the information about the position of the reticle (3).
The exposure apparatus according to other various embodiments includes a reticle exchange unit (10) for holding a plurality of reticles (3), and an exposure control unit (21) for exposing a part of the patterns on the plurality of reticles (3) as overlapping onto the substrate (6).
In the exposure apparatus according to other various embodiments, the output unit (21, 22) outputs plural pieces of information about the position of the reticle (3) when the designated position refers to the overlapping portion.
The exposure apparatus according to other various embodiments includes a selection unit (23) for selecting the information about the position of a reticle from among the plurality of reticles corresponding to the overlapping portion when the designated position refers to the overlapping portion.
In the exposure apparatus according to other various embodiments, the information about the position of the reticle (3) refers to at least one of the position from the center of the reticle (3) and the position from the center of the pattern.
The exposure apparatus according to other various embodiments exposes a pattern on the reticle (3) onto a plurality of exposure areas of the substrate (6), and includes the display unit (22) for displaying a shot map showing the plurality of exposure areas, a designation unit (23) for designating an evaluation position on the shot map, a storage unit (25) for storing the information about an error of the exposure as corresponding to the plurality of exposure areas, and the output unit (21, 22) for outputting the information about the error of the exposure at the designated position.
The exposure apparatus according to other various embodiments is operated in the step-and-repeat system or the scanning system.
In the exposing method according to other various embodiments, a pattern on the reticle (3) is exposed onto the exposure area of the substrate (6). The method includes a step (S1, S11, S21) of displaying a shot map showing the exposure area, a step (S2, S12, S22) of designating an evaluation position on the shot map, and a step (S6, S18, S29) of outputting the information about the position of the reticle corresponding to the designated position.
The exposing method according to other various embodiments includes a step of exposing a part of the patterns on the plurality of reticles (3) as overlapping onto the substrate (6).
The exposing method according to other various embodiments includes a step of outputting plural pieces of information about the position of the reticle (3) when the designated position refers to the overlapping portion.
The exposing method according to other various embodiments includes a step (S16, S26) of selecting the information about the position of a reticle from among the plurality of reticles corresponding to the overlapping portion when the designated position refers to the overlapping portion.
In the exposing method according to other various embodiments, the information about the position of the reticle (3) refers to at least one of the position from the center of the reticle (3) and the position from the center of the pattern.
The exposing method according to other various embodiments exposes a pattern on the reticle (3) onto a plurality of exposure areas of the substrate (6), and includes a step (S1, S11, S21) of displaying a shot map showing the plurality of exposure areas, a step (S2, S12, S22) of designating an evaluation position on the shot map, a step of storing the information about an error of the exposure as corresponding to the plurality of exposure areas, and a step of outputting the information about the error of the exposure at the designated position.
The storage medium according to the present invention is a computer-readable storage medium storing a computer program for realizing the exposing method for exposing the pattern on a reticle onto the exposure area of the substrate. The computer program executes each of the above described steps of the methods according to various embodiments. By executing the program using a computer, the above described operations can be quickly performed. The storage medium is realized as an internal storage medium such as ROM, RAM, a hard disk, etc., and an external storage medium such as CDROM, a floppy disk, an MD, etc.